The present invention is related to WDM (Wavelength Division Multiplexing) optical networks and, more particularly, to the organization of optical fibers at a WDM network node.
In WDM systems, multiple optical signals having different wavelengths share an optical fiber, each wavelength defining a particular communication channel. This technique has many advantages in implementing optical communication systems including increased capacity and the ability to use passive optical components to redirect a portion of the data flowing along the fiber for processing at an intermediate node. Hence WDM (Wavelength Division Multiplexing) is used herein in this inclusive sense to include any system using optical wavelengths to define channels, such as DWDM (Dense Wave Division Multiplexing), unless the term is clearly stated to refer to the ITU (International Telecommunications Union) defined optical network, which has a grid of specific wavelength communication channels and wavelength spacings between the channels.
Optical networks are organized into ring and mesh networks. In a mesh network, each network node is connected to other nodes by a plurality of optical fibers so the network appears as a mesh topologically. A loop network can be considered as a degenerate case of a mesh network in which each node is connected to two other nodes and appears as a loop topologically.
Many current WDM networks are loop networks, but they are being reorganized as mesh networks. However, in a mesh network the simple arrangement of optical fiber interconnections to other nodes and the add and drop functions in a loop node are replaced by the numerous and complex interconnections of switching elements to several other nodes and for add/drop functions of a mesh node. Not only are the mesh node interconnections complicated, and likely to result in misconnections, but also verification of connections is difficult. Current network systems do not allow for easy installation that guarantee correct connectivity without very complicated test procedures requiring extra hardware.
The present invention addresses at least some of these challenges with optical fiber organizers for a network mesh node which not only reduce the complexity of the interconnections and the possibility of errors, but also facilitate the verification of the node connections.